Conventional MEMS rotation rate sensors require a high mechanical quality of the MEMS element. The quality of the MEMS element is determined essentially by the internal pressure in a MEMS cavity of the MEMS rotation rate sensor. Due to the friction between residual gas and the mechanical oscillating structure of the MEMS rotation rate sensor, energy is continuously withdrawn from the system, which limits the maximum quality in the mechanical system and the maximum quality of the MEMS element.
To set a low internal pressure and a high quality, the sensor wafer and the cap wafer are bonded in a chamber having the desired internal pressure. For example, residual gas and outgassing from the surface facing the cavity limit the achievable minimum internal pressures in the cavity.
The internal pressure may be further reduced and held essentially constant over the service life of the micromechanical component by use of a getter in the cavity.